This is a proposal for the second phase of a three-part process to develop an innovative and efficacious therapy for combat veterans with mild traumatic brain injury (mTBI) and post-traumatic stress disorder (PTSD). Our efforts focus on the use of virtual environments and virtual humans (VEVHs) to treat the cognitive dysfunction and emotional dysregulation that plague so many returning warriors. We have already assembled a dedicated team of clinical and technical experts who have created a prototype VE, and are now developing a VH for combat veterans with mTBI. This proposal continues the development of our preliminary work and allows it to be evaluated by working clinicians and veterans to assure that it is applicable and meaningful. The Centers for Disease Control and Prevention estimates that in the Unites States, 1.4 million individuals will sustain traumatic brain injuries (TBI) per year1. Since 2001, the United States has deployed more than 1.5 million military personnel to Iraq and Afghanistan2. The Defense and Veterans Brain Injury Center estimates that up to 20% of combat veterans returning from Iraq and Afghanistan have sustained some type of TBI. As of 2008, at least 25,000 Soldiers have been diagnosed with TBI, with a projected cost of $14 billion for their care over the next two decades. The symptoms of TBI (which often are accompanied by post-traumatic stress disorder) include disturbances in attention and memory, as well as impaired cognitive processing. Often the most troubling symptoms are behavioral: mood changes, depression, anxiety, impulsiveness, and emotional outbursts. Intolerance of crowds and hyper-vigilance are also common. Behavioral therapy, a mainstay of rehabilitation treatment, generally requires that veterans be able to organize and negotiate daily activities and interact with the general public to meet scheduled appointments, stressing the very areas where many are profoundly impaired. New therapeutic options that can be delivered to veterans at home, and that can augment current processes are needed. Fortunately, VEVHs hold the potential to answer these concerns. VEVHs are easily accessible, intuitive, and effective forms of virtual reality that provide secure real-time interaction between multiple users. Many younger warriors are not only familiar with, but comfortable and fluent in virtual realities through their exposure to electronic gaming. Our novel VEVHs present realistic simulations of everyday encounters providing opportunities for interactions between warriors and therapists in a fully immersive, customizable, controlled, and less-threatening environments. Because they are computer-driven, these interventions can be delivered either face-to-face or at home using tele-health technology. Because the warrior and therapist are connected in the virtual world, the therapist does not have to be present in the same room or even in the same time zone in the real world. The goal of this application is to build two interactive VEVH scenarios which will have been extensively vetted by clinicians and veterans, and thus will be ready for the process of clinical trials by the end of the grant period.